Justification:
Due to its large and either stable or increasing population, on a global scale the Harbour Seal is considered to be Least Concern. However, for conservation concerns at a somewhat finer spatial scale, it is prudent to assess each of the subspecies separately as some populations are small and declining.

Harbour seals are one of the most widespread of the pinnipeds. They are found throughout coastal waters of the Northern Hemisphere, from temperate to Polar Regions. Five subspecies are recognized: P. v. vitulina occurs in the eastern Atlantic from Brittany to the Barents Sea in north-western Russia and north to Svalbard, with occasional sightings as far south as northern Portugal; P. v. concolor occurs in the western Atlantic from the mid-Atlantic United States to the Canadian Arctic and east to Greenland and Iceland; P. v. mellonae only lives in a few lakes and rivers in northern Quebec, Canada, that drain into Hudson and James Bays (geological changes prohibit these seals from leaving this freshwater habitat); P. v. richardii is found in the eastern Pacific from central Baja California, Mexico to the end of the Alaskan Peninsula and possibly to the eastern Aleutian Islands, and; P. v. stejnegeri ranges from either the end of the Alaskan Peninsula or the eastern Aleutians to the Commander Islands, Kamchatka and through the Kuril Islands to Hokkaido in the western Pacific.

Combining recent estimates yields a world-wide population of 350,000 to 500,000 animals.

P. v. vitulina - Population dynamics of regional subpopulations vary dramatically, with recent large-scale declines in the northern UK populations (Thompson et al. 2001, Lonergan et al. 2007), rapid increases punctuated by major population crashes due to disease events in the Wadden Sea, southern England, Kattegat and Skagerrak populations and gradual increase after near extinction in the 1970s in the Baltic (e.g. Heide-Jorgensen and Harkonen 1988, Harkonen et al. 1999, 2002, 2005, 2006). Populations in Svalbard and the Baltic Sea, are low, both in the hundreds, although they are not considered to be separate subspecies. There are some morphological differences at least in the Svalbard population (Lydersen and Kovacs 2005). Overall the population of P. v. vitulina has increased since the 1970s.

P. v. concolor - Canadian populations declined during the 1970s from approximately 12,000 to 4,000. They have probably been increasing since the early 1980s with the exception of the Sable Island subpopulation that declined from a maximum pup production of 600 in 1989 to et al. 2003). Populations in West Greenland, Iceland and Norway are depleted as a result of hunting (Bjorge 1987, Hauksson 1992, Teilmann and Dietz 1994, Henriksen et al. 1997). Harbour seals in the eastern USA have increased at 6.6% p.a. since 1981, recovering from results of bounty hunting which ceased in the 1960s (Gilbert et al. 2005). Overall the population of P. v. concolor has been stable or increasing since 1980.

P. v. richardii - Population dynamics of regional subpopulations vary dramatically. Large-scale, long-term declines in Gulf of Alaska from the 1970s to the early 1990s with >60% declines, have apparently stabilized, with the population experiencing slight increases since the early 1990s (Pitcher 1990, Frost et al. 1999, Jemison and Kelly 2001, Boveng et al. 2003, Mathews and Pendleton 2006, Jemison et al. 2006). Long-term population increases from the 1970s up to early 1990s appear to have reached an asymptote in British Columbia, Washington, Oregon, and California. Overall the P. v. richardii populations has been stable or increasing since the early 1990s.

P. v. stejnegeri - Population dynamics of this subspecies are not well documented, but the population in the Kuril Islands appears to have increased slightly from 2,000-2,500 in the early 1960s (Belkin 1964), and again increased to around 3,000-3,500 individuals in 2000 (Trukhin 2002). Similarly, in the Commander Islands the subpopulation increased from around 2,000 in the early 1960s to around 3,000-3,500 in the early 1990s (Burdin et al. 1991) and is thought to be stable. The population in Japan is small, estimated at 350 individuals in late 1980s, having declined due to heavy hunting pressure (Hayama 1988). This population is still thought to be subject to high by-catch rates in trap net fisheries and is shot by fishermen coastally Wada et al. 1991).

P. v. mellonae – This subspecies lives in lakes and rivers of the Ungava Peninsula, Canada. It is thought to number some 120-600 individuals and may be the subspecies most at risk to extinction, due to low population numbers and potential effects of hydro-electric developments (Smith 1997).

Adult males are up to 1.9 m long and weigh 70-150 kg, females 1.7 m and 60-110 kg. At birth, pups are 65-100 cm and 8-12 kg (Burns 2002).

Harbour seals are mainly found in the coastal waters of the continental shelf and slope, and are also commonly found in bays, rivers, estuaries and intertidal areas. On land, harbor seals are usually extremely wary and shy unless habituated to human activities and noise sources in their vicinity. It is almost impossible to approach them when they are ashore without stampeding them into the water. Most harbour seal haul-out sites are used daily, based on tidal cycles and other environmental variables, although foraging trips can last for several days. Although generally considered a non-migratory species with a high degree of site fidelity to a haul out, juvenile dispersal, emigration and establishment of new haul out sites are all possible reasons for long range movements of harbour seals (Burns 2002).

Harbour seals are gregarious at haul-out sites. However, they usually do not lie in contact with each other. They will haul out on rocks, sand and shingle beaches, sand bars, mud flats, vegetation, a variety of man-made structures, glacial ice, and to a very limited extent sea ice in some areas. They usually lie close to the water to permit a rapid escape from threats. Sex and age segregation is common in most populations (Kovacs et al. 1990). At sea, they are most often seen alone, but occasionally occur in small groups. Localized aggregations can form in response to feeding opportunities and concentration of prey.

Male harbour seals become sexually mature when four to five years old. Female harbour seals usually become sexually mature when three to five years old. Gestation lasts 10.5-11 months, including a 2+-month delayed implantation. Throughout the range, the time of birthing varies widely and may follow a latitudinal cline (Temte 1994). Peak pupping date varies from mid March to early September. The mating system is promiscuous, or weakly polygynous, with males defending underwater calling sites (e.g. Van Parijs and Kovacs 2002). Mating usually takes place in the water, with females coming into oestrus around a month after giving birth. Moult follows the pupping and mating season. The timing of onset of moult depends on the age and sex of the animal with yearlings moulting first and adult males last (e.g. Reder et al. 2003). Most harbour seal monitoring programs are based on counts obtained during the moult and are therefore subject to possible biases due to changes in age and sex structure of the population.

Most pups shed their silvery gray lanugo coat in the uterus before birth. Exceptions to this include pups born prematurely, and some that are born early in the breeding season. Pups usually enter the water rapidly after birth, and because of tidal inundation at many sites used for birthing, this often occurs in hours (Burns 2002).

Harbour seals are generalist feeders that take a wide variety of fish, cephalopods, and crustaceans obtained from surface, mid-water, and benthic habitats (e.g. Olesiuk et al 1990, Payne and Selzer 1989). Their diet is highly varied, and animals from different populations and areas show differences and there is also variation associated with seasonal changes in the abundance of prey (e.g. Harkonen 1987, Andersen et al. 2004). Generally, a few species dominate the diet at any one location and time of year. Although primarily coastal, dives to over 500 m have been recorded (Burns 2002). Harbour seals also take many commercially important fish species such as Atlantic cod, many kinds of salmon, herring, and flatfishes to name a few, and this aspect of their foraging puts them into conflict with coastal fisheries.

Longevity is typically 35 years for females and 25 years for males, but is lower in P. v. stejnegeri and P. v. richardii which are reported to live to approximately 20 years for males and 30 years for females. Predators include killer whales, great white and Greenland sharks and possibly other shark species, Steller sea lions and walrus, gulls and ravens and in southerly locales feral dogs and eagles. There is no information on polar bear, brown bear, and wolf predation on harbor seals, but all are possible predators.

Harbour seals live in coastal areas many of which are heavily fished. As a result there are entanglement and by-catch issues which may be significant in some populations e.g. in northern Japan (Burns 2002). Over fishing, oceanographic regime shifts and global climate change may impact food chains harbour seals depend upon for prey.

Historically, there have been organized population reduction programs and bounty schemes in several range states of countries, largely because of perceived. Hunting and/or licensed killing to protect fisheries still occurs in Norway, UK and Iceland and subsistence hunting is allowed in Greenland and the United States (Alaska). In Greenland and Iceland there are indications that hunting is responsible for continuing population declines.

Mass die-offs from viral outbreaks have claimed thousands of harbour seals on both sides of the Atlantic, but most notably in Europe. In 1988 more than 20,000 harbour seals are estimated to have died from a phocine distemper virus (morbillivirus) epidemic in European waters (Dietz et al. 1989, Reijnders 1989). A similar outbreak in 2002 killed approximately 30,000 (Harkonen et al. 2006). Other disease outbreaks occurred both before and after this large epidemic in both Europe and the western North Atlantic, but resulted in much smaller levels of mortality. Influenza from an avian source killed approximately 500 harbour seals in the North-eastern United States in 1979 and 1980 (Burns 2002). Potential for exposure to disease is probably increased by the natural behaviour of this species to haul out on near shore and at coastal mainland sites. As a result terrestrial carnivores, waste from human populations as well as contact with human pets and feral animals associated with human populations creates an increased risk of exposure to communicable diseases.

Because many harbour seals live and feed in close proximity to large populations of humans they are exposed to and can accumulate high levels of industrial and agricultural pollutants in some parts of their range (see Reijnders 1978, 1985, 1986, Aguilar et al. 2002, Wang et al. 2007); while some northern populations have very low contaminant levels (e.g. Wolkers et al. 2004). Immuno-suppression is one affect regularly attributed to exposure to high levels of certain organochlorines and these and other contaminants probably contribute to poor condition and overall fitness of a number of animals in some areas. Both chronic oil spills and discharges and episodic large scale spills cause direct mortality and have long term impacts on harbour seal health and their environment. Some additional examples of threats and impacts to harbour seal populations are given below.

P. v. stejnegeri, of the western Pacific, numbers approximately 7,000 animals. Fishery related mortality in the small Japanese population is a cause for concern (Wada et al. 1991). However, low levels of human activity in the Kurils and protected status within nature reserves in the Commander Islands means that there is no obvious anthropogenic threat to the bulk of the population.

P. v. mellonae numbers only some 120-600 animals which are restricted to the Seal Lakes (Lac des Loups Marin) of the Ungava Peninsula, Canada. This subspecies is at risk due to low population numbers and unknown effects of James Bay II hydroelectric development which may reduce the water level in the seal lakes by 20 cm. This might have impacts on mortality of seals in winter and altered hydrographic conditions could potentially affect the seals’ prey.

P. v. richardii has shown dramatic reductions in the recent past in one large part of its range, Gulf of Alaska and Prince William Sound. Although part of this decline may be related to the effects of the Exxon Valdez disaster, the overall decline in Gulf of Alaska is unexplained.

Subpopulations of P. v. vitulina in the Northern UK have recently declined by around 50% in less than 10years. The cause of this decline is unknown. The Icelandic population has declined by 5% p.a. since 1980, which is thought to be due to direct hunting. Populations in Svalbard and the Baltic Sea, which are both small are protected. Competition with increasing gray seal populations may have been responsible for declines in the mid-latitudes and further increases in grey seal populations seem likely in the North Sea. Rapidly increasing development of offshore wind generated power means that the levels of industrial activity and noise are increasing in the foraging areas of resident harbour seals. To date, there is little information available to assess the potential impacts of such disturbance.

Historical population reductions of P. v. concolor along the USA coast were probably due to hunting that has now ceased. The rapid decline in the Sable Island population may have been due to a combination of shark predation (Lucas and Stobo 2000) and competition with grey seals (Bowen et al. 2003); the continued increase of grey seal populations in Canadian and US waters could produce a more widely spread decline.

In the United States the harbour seal is protected from all but subsistence hunting by the Marine Mammal Protection Act of 1972, which also prohibits importation of parts or products from all seals. Coastal reserves in Norway which exclude commercial fishing have been shown to reduce harbour seal mortality because of the generally restricted movements of this species along the Norwegian coast. Hunting is now prohibited in the Wadden Sea area (The Netherlands, Germany, Denmark, and Swedish waters) (Reijnders et al 1993), Swedish Baltic, Eire and UK (Harwood 1987). Licensed killing to protect fisheries is allowed in UK, Canada and USA. Illegal hunting probably occurs throughout the harbour seal's range. The harbour seal population in Svalbard is on the national Red List for Norway and is afforded complete protection.